CAEN
T
Electronic Instrumentation
his is the only synthesizer of random
pulses that is also an emulator of radiation
detector signals with the possibility to configure
the energy and time distribution.
Digital Detector
Emulator
Your Powerful User-friendly Solution for the
Emulation of Any Detection Setup
The Digital Detector Emulator is a multichannel instrument for the emulation
of radiation detection systems. The algorithm is initialized by a reference
pulse shape, with statistical distribution of amplitude and time. Then a
statistical stream of events is generated according to the input distributions.
The events can be also selectively summed together simulating the pile-up
phenomenon. An arbitrarily generated noise and a baseline drift can be
superimposed to each pulse.
Therefore, the instrument is not a pulse generator of recorded shapes, but it
is a synthesizer of random pulses compliant with programmable statistical
distributions of energy spectrum, time distribution, and pulse shape.
The stream of emulated signals becomes a statistical sequence of pulses,
reflecting the programmed input features (e.g. energy spectrum, time
distribution, noise, signal shape, etc.). When the emulation process is reset,
the kernels of generators can be either re-initialized with new random data
making the sequence always different, or they can be stored to reproduce
the same sequence many times.
The Digital Detector Emulator is able to emulate two different radiation
sources at a time on the two output channels and to provide them either
with fully independent parameters, or with some of them correlated. For
example the events can be time correlated (steps of 12 ps), or a subset of
events can share the same energy spectrum. It is also possible to set the
channels in a master/slave configuration, where the first channel works as a
trigger for the second one.
• Emulator/Pulser/Function Generator
operating mode
• Energy spectrum emulation (pre-defined or
measured in real setup)
• Time distribution emulation
• Pile-up emulation
• Noise (Gaussian, 1/f, random walk) and
periodic interference emulation
• Baseline drift
• Custom signal shape emulation (predefined or measured in real setup)
• 12 ps/step programmable analog delay
generator
• Correlated events generation on the two
output channels
• Multiple shape on the same channel for
testing the pulse shape discrimination
• Continuous and pulsed reset pre-amplifier
emulation
Small details
Great differences
Digital Detector Emulator
EMULATION PRINCIPLE
The use of digital pulse processing techniques is widely used in many
fields of application of radiation measurements, for example in the pulse
height analysis, in the pulse shape discrimination, in the time-to-digital
and amplitude conversion, etc. Since those systems and algorithms
are becoming more and more complex, it is very useful to have precise
simulations of the detection and acquisition systems. This can help, for
instance, in preliminary feasibility studies or in tests
to understand the system response itself, as well
as for later debug purposes. Another advantage is
the reduction in time of radioactive source use, thus
reducing the risk for the experimenter’s health.
possible to emulate two different shapes with programmable mixture
on the same output channel. This feature allows to test the pulse shape
discrimination.
While the integrator circuit emulates the behavior of a real analog pulse,
the memory-based system emulates the pile-up effect starting the readout
of one of the 16 memories as soon as the trigger fires. The output of all 16
memories is then summed to produce a piled-up signal.
All of this encouraged the idea of developing a digital
technique to emulate the radiation signals which can
resemble as much as possible the real experimental
data.
Currently, there are electronic instruments able to
generate analog signals with exponential shape, fixed
amplitude, and exponential time distribution. Anyway,
they cannot modulate the amplitude according to a
given energy spectrum. This issue has been overcome
by recording long sequences of events (the so called
“Arbitrary Waveform Generators”), being strongly
limited by the memory size, and therefore by the
signal length and the counting rate.
The CAEN Digital Detector Emulator not only is able
to perform such standard features, but is also able to
generate an electrical signal that fully emulates real
detection systems. The user can control all the signal
features, providing as input the statistical distributions
of energy spectrum, time distribution, and pulse
shape. The output stream of events is a statistical
distribution itself that emulates the input energy and
time spectra.
Advanced features allow also to simulate the noise,
the interferences, the pile-up, the baseline drift, and
the correlations among channels. The sequence of
data can be either re-initialized with new random data to have always
different sequences, or with the same starting seeds to reproduce the same
sequence many times. The possibility to fine control each input parameter
allows to study any variation of the system and to predict the outcome of
the analysis algorithms. Moreover, the user can test specific cases and push
the parameters to their physics limits to test the readout electronics.
EMULATION PROCESS
The emulation algorithm generates pseudo-random events according to
the input statistical distributions of energy spectrum, time distribution,
and pulse shape. The input energy spectrum is used to simulate the pulse
amplitude, while the input time distribution to simulate the time distance
between two consecutive pulses, and the pulse shape to choose among
different shapes. The output signal statistically reproduces the input energy
and time spectra.
Block scheme of the event generation process.
The signal can be combined with the noise to have a more realistic emulation.
The system is able to emulate white noise, 1/f noise, and random walk. It is
also possible to mix those noise sources, as well as to add the interferences
among the events. The 1/f noise can be adjusted both in frequency and in
amplitude. It is also possible to emulate the periodic noise due, for example,
to the switching power supply with either fixed or random amplitude and
time jitter.
The system emulates the drift in time of the baseline value following a
programmable generic profile. Through an interpolation function, it is
possible to achieve long lasting drifts up to 1 s.
The system can be controlled from the user PC by a software tool that allows
to program the whole system in few clicks. An on-board FPGA performs
up to billions of operations per second, generating a digital stream that is
then converted to an analog signal by two 16-bit 125 MSPS DAC. The analog
signal can be provided on the output w/o a filter to get low noise or sharp
rise time. The system owns 4 MB RAM memory to store either predefined
function sequences or the AWG waveform samples (see later).
The signal shape can be generated either by a digital equivalent integrator
circuit, or by a set of 16 memories. The first algorithm allows the generation
of exponential signals (adjustable rise/decay time) with no limitation in
the number of piled-up events. The second one allows the generation of
arbitrary programmable shapes up to 16 events in pile-up.
The FPGA generates the time based trigger signal that enables the signal
generation as a function of the programmed time distribution. It is also
Block diagram of the Digital Detector
Emulator.
Digital Detector Emulator
Firmware structure for the
signal generation
CORRELATED EVENTS EMULATION
The instrument is able to emulate two different radiation sources at a
time and to provide them either on the two outputs, or to mix them (with
known mixing parameter) on the same output. The two emulation chains
can either have fully independent settings (energy spectrum, signal shape,
time distribution of the events, noise characterization, etc.), or they can have
some of the parameters correlated. For example, a correlated subset of the
two output channels can share the same energy spectrum and the same
generation time, or it is possible to have a fixed time correlation among the
events of the two channels. Moreover, it is possible to set the instrument in
a master/slave configuration where the first channel works as a trigger of
the second one. The correlation among the events is useful, for instance, in
debugging PET systems, or in those experiments involving the time of flight
measurement, or to simulate the detection of small signal events expected
in a large amount of background. Three operation modes are available:
NOISE EMULATION
The system allows the emulation of several noise contributions, such as
white noise, 1/f, random walk (baseline drift). It is also possible to acquire
from the oscilloscope a periodic interference noise and to add it to the
output signal, with variable amplitude and time jitter.
1) Channel 1 (CH1) is the time shifted copy of Channel 2 (CH2) (12 ps step);
2) CH2 has its own statistics generator (i.e. different spectrum, different
noise, etc.) but is triggered by CH1 (delayed by 12 ps step);
3) a third emulator channel (with separate statistic properties) generates
correlated pulses for both CH1 and CH2. In this way, only some events of
the two channels are correlated.
The delay line for the time correlation is thermalized through a Peltier cell to
minimize the thermal drift.
Generation of correlated events. CH1 in red, CH2 in blue. The yellow mask shows a correlated event sharing
the same energy and timing in both channels.
Final analog output of the Digital Detector Emulator.
PSEUDO-RANDOM GENERATION
When the emulation process is reset, the kernel of pseudo-random
generators can be re-initialized with new data making the sequences always
different. To obtain many times the same sequence of pulses, the generator
can be re-initialized with the same seed values.
Furthermore, it is possible to store up to 500k pairs of Energy and Time
information in the internal RAM memory to generate pre-defined sequences
of 500k events.
SPECTRUM IMPORTER
Import of CSV and ANSI N42.42 spectrum files. The software automatically readjusts the input bin spectrum to the 16384 bins of the emulator. The software
allows to stretch the spectrum, and to shift the energy peaks. For multiple
spectra ANSI N42.42 files, it is possible to choose the spectrum to import.
MULTISHAPE EMULATION
To debug pulse shape discrimination systems, the emulator is able to
generate two different programmable shapes with specific programmable
statistics. It is also possible to generate pile-up events with different shapes.
Two different shapes in the same output channel
The GUI shows the input spectrum (left) and the resulting imported spectrum (right).
Digital Detector Emulator
DT5800
NEW
Desktop Digital Detector Emulator
This is the most advanced system in the world
for real-time emulation of random signals from
radiation detectors.
Operating modes:
PULSER
Classic pulser operation. The system allows to set
the signal amplitude, the signal rate, and to choose
between constant and Poisson distributed rate.
Pulser/Emulator/Function Generator operating modes
Energy spectrum emulation
Time distribution emulation
Custom signal shape emulation
Pile-up emulation
Noise and periodic interference emulation
Baseline drift
12 ps/step programmable delay generator
Correlated signals generation on the two output
channels
• Multiple shape on the same channel for testing of pulse
shape discrimination
• Continuous and pulsed reset pre-amplifier emulation
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DETECTOR EMULATOR
In the detector emulator operating mode, the
system is able to emulate with high accuracy a
radiation detection system from the detector
output to its related front-end electronics. The user
must provide: the signal shape distribution, the
required energy spectrum, the time distribution,
the noise characterization, and the baseline drift.
The signal shape can be generated either by using
the system internal database, or using recorded
shapes from the experimental setup. The same is
true for the energy spectrum. It is possible to create
several emission lines through the tool itself, or to
import a file in the format of CVS/ANSI N42.42, or to
use the internal database electronics. The user can
choose a Poisson or any arbitrary time distributions.
It is also possible to emulate white noise, 1/f
noise, random walk, as well as interferences. The
characterization of the baseline drift can be also
added.
CORRELATED EVENT GENERATOR
The instrument allows to generate correlated
events with fixed time shift (time steps of 12 ps). The
two signals can have either the same or different
statistical distributions. Furthermore, it is possible
to generate a subset of events according to a fixed
energy spectrum, being statistical uncorrelated
from the background events.
ARBITRARY WAVEFORM GENERATOR
The instrument comes with 1M points of RAM
memory per channel to store and then reproduce
the events from pre-defined functions.
The Desktop Digital Detector Emulator is available
in single or dual channel version.The dual channel
model allows the event correlation.
USB 2.0 communication interface.
Software tool compliant with Windows OS. Shape
and spectrum files import from any Digital Pulse
Processors, Digitizers, and oscilloscopes. Model
shape generation (with no noise) from input
waveforms.
Programmable digital outputs: Trigger in, Trigger
out, and Gate.
Software GUI for the Digital Detector Emulator.
Code
Description
WDT5800DXAAA
DT5800D - Dual Channel Desktop Digital Detector Emulator with channel correlation
WDT5800SXAAA
DT5800S - Single Channel Desktop Digital Detector Emulator
NDT6800
NIM/Desktop Digital Detector Emulator
• Same features of the
desktop version
• 2 units, NIM standard
• Either backplane or AC-DC
power supply
• USB 2.0 interface
NEW
The NIM Digital Detector Emulator comes with the same
operating modes of the Desktop version: pulser mode, detector
emulator, correlated events generator, and arbitrary waveform
generator. The whole electronic system is integrated in a twounit NIM module for standard NIM crate integration.
USB 2.0 communication interface. Front panel USB connector.
Either NIM backplane or AC-DC power supply. The latter allows to
use the crate stand-alone, without the NIM crate. Active cooling
system for non-cooled NIM crates.
The delay line for the time correlation is thermalized through a
Peltier cell to minimize the thermal drift (temperature stability of
about 0.03°C).
OneTOUCH Interface for the basic
software configuration.
Code
Description
WNDT6800DXAA
NDT6800D - Dual ChannelNIM/ Desktop Digital Detector Emulator with channel correlation
WNDT6800SXAA
NDT6800S - Single Channel NIM/Desktop Digital Detector Emulator
Digital Detector Emulator
Applications
Remote Experimentation
CAEN digitizers and the dual digital MCA DT5780 allow to acquire signals from
radiation detectors and to make digital pulse processing through dedicated
firmware. It is therefore possible to acquire both the waveforms and the energy
spectrum, then saving those information in two files. The files can be imported
in the emulator software and used as a model for the emulation process,
without the presence of any radioactive sources or detectors.
specific radioactive sources. This gives the great advantage to have a realistic
emulation, limiting the use of dangerous radioactive sources.
The emulation algorithm allows for additional fine control of the rate and the
noise. It is also possible to reproduce the same event sequence by storing the
starting seed of the pseudo-random generation.
Pulse Shape Discrimination between neutrons and gamma
Correlated Events
Digital Detector Emulator used in combination with the DT5780 MCA
Time To Digital Converter
The Digital Detector Emulator can be coupled with a CAEN TDC module for a
precise test of time resolution.
Many applications require the acquisition of coincidence events among
different channels. The Digital Detector Emulator allows to generate a subset
of common events in the two channels, that shares the same energy spectrum.
It is therefore possible to program the two analog outputs to emulate two
uncorrelated backgrounds with only some of the events in common. Only when
the readout coincidence between the two channels is enabled (for example using
CAEN digitizer families with DPP firmware), the correlated spectrum comes out.
Usually, a delay generator or a simple pulser allows the generation of signals
with fixed amplitude and shape. The Digital Detector Emulator allows to test
time resolution in more generic configurations, using signals with variable
amplitude and shape.
Pulse Shape Discriminator
There are many experiments where the discrimination among particles is
made through their different waveform shape. This is, for example, the case of
neutron-gamma discrimination. The Digital Detector Emulator, being able to
simulate two different pulses, allows to simulate the neutron-gamma different
response, in order to make tests and debug studies without the presence of the
Energy spectrum correlation among channels
Additional Features
Arbitrary Waveform Generator
The Digital Detector Emulator integrates an
Arbitrary Waveform Generator with up to
1Mpoints per channel to emulate the analog
signal saved by the user (maximum sampling
rate of 125 MSPS).
Furthermore, the DDE comes with a predefined waveform generator able to reproduce
sinusoidal waveforms, square waves, ramp
waves (also asymmetric), saw- tooth, pulse
(square wave with duty cycle, adjustable
and possibly asymmetric slopes), sinc, etc.
Adjustable rate from 1mHz to 10 MHz.
Automatic adjustment of the initial phase of the
sinusoid waveform.
ps step. Both the pre-defined waveforms and those imported by the user can be
delayed.
Isotopes database
The software provides an interface to pick the mono-energetic lines of several
isotopes, and arbitrarily create a complex energy spectrum. It is possible to
calibrate the output energy dynamic, and to associate a specific resolution to
each line.
The noise generator produces a statistical
distribution of the noise, using a uniform
distribution as numeric source. Pseudo random
noise distributions can be generated.
Arbitrary Delay Generator
The Arbitrary Waveform Generator function can
be combined with the Arbitrary Delay Generator
function to shift the two channel outputs by a 12
Arbitrary Waveform Generator GUI
Isotopes database GUI interface
Digital Detector Emulator
Technical Specifications
Energy emulation features
Baseline
Software and interfaces
• Single line (65535 selectable levels)
• Spectrum emulation (16384 bins with 14 bit
resolution)
• ± 4 V output range
• 16 bit D/A converter
• Baseline drift programmable with arbitrary shape
• Windows-based user interface managing more
than one emulator
• USB 2.0 and Ethernet interfaces
Correlated events emulation
• Three operation modes: 1) Channel 1 (CH1) is
the time shifted copy of Channel 2 (CH2) (12 ps
step); 2) CH2 has its own statistics generator (i.e.
different spectrum, different noise, etc.) but is
triggered by CH1 (delayed by 12 ps step); 3) A
third emulator channel (with separate statistic
properties) generates correlated pulses for both
CH1 and CH2. In this way, only some events of the
two channels are correlated
• 12 ps step programmable delay (from 0ps to 32us),
18 FWHM, 60 ppm linearity
• Temperature stabilization of the delay line
Time emulation features
• Constant rate emulation
• Poisson distribution
• Programmable statistical generation of events
(256 bins, 8 bit resolution)
• Up to 11 MCPS, both in constant and statistical
emulation
• Integrator circuit emulation without pile-up
limitation
• Up to 16 pile-up events in the memory based
algorithm
• Programmable dead-time and emulation of
parallelizable and non-parallelizable machines
• 20 ns to 10 ms exponential decay time
Digital I/O
• 2-input and 2-output programmable
• Trigger out, analog saturation warning, machine
overload sensing
• Trigger in, random number generator control
(reset / play / pause), gating, baseline reset
Signal shape
RNG (random number generator)
• 4096 points to store waveforms
• Arbitrarily programmable shapes
• Shape length from 64 ns to 26 μs (w/o
interpolation) / 26 ms (interp.)
• Separated rising and falling edge interpolation
• Up to two separate shapes mixed on the same
channel with independent statistic
• 8 independent LFSRs with 64 bits generate the
base for the statistical emulation
• Possibility to randomize the seeds of each RNG
independently
• Possibility to initialize the RNG with fixed seeds
to get repeatable sequences to test different
processing architectures
• Generation of finite length streams of pulses to
debug step-by-step the DUT
Noise emulation
•
•
•
•
White noise emulation (BW 62.5 MHz)
1/f noise emulation
Random Walk (baseline drift)
Interference generation (e.g. possibility to record
spikes from switching power supplies and inject in
the output signal)
• Interference generation with fixed amplitude and
frequency or randomly modulated in amplitude
and injection time
Emulation of continuous and pulsed reset preamplifier
Programmable sequence
• 500 kpoints of memory/CH to store a sequence of
pairs (energy, time of occurrence) to generate long
predictable and defined sequences of pulses
Arbitrary waveform generator
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DT5800D web page >>>
• 1 Mpoints/CH to store any arbitrary waveform
• Function generation: sin, square, ramp, saw, pulse,
sinc up to 10 MHz
.
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CAEN
Tools for Discovery
Copyright © CAEN SpA - 2015
All rights reserved. Information in this publication supersedes all
earlier versions. Specifications subject to change without notice.
Printed in March 2015 - ADOCUME000100 - BF3108 - rev02
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CAEN SpA
CAEN GmbH
CAEN Technologies, Inc.
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